Verifying speaker operation during alarm generation
US7911353B2 · kind B2 · utility
Assignees
Inventor
Key dates
| Filing date | Jun 2, 2008 |
| Grant date | Mar 22, 2011 |
| Priority date | — |
| Expiry date | Apr 28, 2029 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61M2205/43
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
The patent discloses a method of verifying that a dialysis machine audio alarm has been sounded. The method senses a waveform of electric power, such as a waveform of the current or voltage that drives a speaker. When the speaker produces sound, power consumption changes the waveform in a manner that is detectable by electrical and electronic sensors. The amplitude envelope and frequency or period of the waveform is specific to the electrical and mechanical characteristics of the speaker. The waveform may be detected by a current-sensing resistor in series with the speaker power source, by a non-contact current transformer or hall-effect sensor, or may be sampled by an ADC. A computer program then compares this resulting signal to an expected signal or waveform and verify the speaker is working. If the speaker is not working, the machine sends a visual alarm or places itself in a safe state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.